Allie-Rose is a student at OCD. She's described as a black-haired and green-eyed beauty that is about a foot taller than every girl in the Pretty Committee's grade.
According to Massie Block, she is too tall to be in the Pretty Committee even though her wardrobe is described as fabulous and filled with "the desirables". It's considered a waste because everything would be too long to share.
When the Pretty Committee returns to OCD after being expelled, Allie-Rose is the first to notice. She even dropped her stack of books and began to clap with others joining in as they made their grand re-entrance.
It's revealed in Sealed with a Diss that when Burberry started using fur, Massie boycotted the fashion label and forced Allie-Rose to make signs that said 'when plaid goes bad' and hang them around the school. This lead to everyone besides the Pretty Committee thinking that it had been Allie-Rose's idea, including Skye Hamilton.